Conventionally, HTML injection is a form of content rewriting that allows arbitrary injection of data into HTTP response forwarded from a server to a client by an intermediate device. However, conventional techniques for establishing frequencies typically result in inaccuracies on multi-core intermediate devices because, in typical environments, the frequency at which to inject data into responses is specified for the intermediate device as a whole rather than for particular cores on the intermediate device. Further, components executing within one core typically work independently at runtime from corresponding components executing within other cores on the intermediate device and do not synchronize with the corresponding components on statistics and runtime counters, potentially resulting in additional inaccuracy on multi-core intermediate devices.